What’s my max?
Estimate your one-rep max from any set with Epley, Brzycki, Lander and four more, see how far they agree, and get a percentage table rounded to weights you can load.
About the one-rep max calculator
Your one-rep max (1RM) is the most you could lift for a single rep with good form. Testing it is tiring and a little risky, so most lifters estimate it from a set they have already done: a weight and how many reps it took.
This calculator does that with seven published formulas, shows how closely they agree, and turns the result into a table of training percentages rounded to weights you can actually load.
How it works
The headline number is the Epley formula: 1RM = weight × (1 + reps ÷ 30). It is the formula the Splyt app uses for personal records, so the site and the app give the same answer for the same set. A single is taken as the max itself.
Six more run alongside it: Brzycki (weight × 36 ÷ (37 − reps)), Lander, Lombardi (weight × reps^0.10), Mayhew, O’Conner (weight × (1 + 0.025 × reps)) and Wathan. Each was fitted to a different group of lifters, so they spread apart as the reps climb. They agree best between three and six reps; past ten, every formula is guessing.
The percentage table runs Epley backwards (reps ≈ 30 × (1 ÷ percentage − 1)), so the reps listed beside each load agree with the max at the top. Loads are rounded to 5 lb or 2.5 kg, the smallest jump most gyms can make.
A worked example
Say you benched 225 lb for 5. Epley gives 225 × (1 + 5 ÷ 30) = 262.5 lb. The other six formulas land between 253 lb (Brzycki) and 268 lb (Mayhew), so a sensible guess for your max sits somewhere in that band.
From that max the table suggests 235 lb for a hard triple (90%), 210 lb for about 8 reps (80%) and 185 lb for sets of 13 or so (70%). In kilograms, 100 kg for 5 works out at 116.7 kg.
Questions
How accurate is a one-rep max calculator?
For a hard set of three to six reps, an estimate usually lands within a few percent of a tested max. It gets less reliable with higher reps, with sets that had plenty left in them, and on lifts the formulas weren’t built from. Use it to plan training, not to predict a meet.
Which 1RM formula is best?
None is best for everyone. Epley and Brzycki are the most widely used and give the same answer at exactly ten reps; below ten, Epley reads a little higher. If the seven formulas agree closely for your set, it doesn’t matter much which one you pick.
Should I test my one-rep max instead?
Most lifters don’t need to. An estimate from a hard set is good enough to set training weights and costs far less recovery than a true max attempt. If you compete, test it as part of a planned peak.
Why are the percentages rounded?
So you can load them. The table rounds every row to 5 lb or 2.5 kg, two of the smallest common plates. The 100% row is the max itself, unrounded, and tapping a row opens it in the plate calculator.
Does Splyt track my max automatically?
Yes. The Splyt app estimates a max from every set you log with the same Epley formula. Signed in, this page opens on your most-trained lift at its best recent set, with its trend over the year.
Related tools
- RPE calculator — Effort to load, and a set back to a max.
- Barbell plate calculator — The plates for any weight, in the colours on the rack.
- Strength standards calculator — Where your bench, squat, deadlift and press sit for your size.
Splyt is a workout tracker for iPhone and Apple Watch that works these numbers out from every set you log. Get Splyt free on the App Store · See what it does · All 12 tools · Workout split guides